Vapor/liquid distributor for fixed-bed catalytic reaction chambers

ABSTRACT

A method and distributor device for effecting the uniform distribution of a mixed-phase vapor/liquid reactant stream across the upper surface of a fixed-bed of catalyst particles. Mixed-phase reactants or components are first separated into a principally vapor-phase and a principally liquid-phase. These separated phases are then re-mixed in a manner which creates a vapor/liquid froth; the latter being re-distributed to the upper surface of the bed of catalyst particles. Briefly, the distributor comprises three annular-form, catalyst-free volumes which are defined by the interior surface of said chamber and three cylindrical walls in concentric relationship therewith.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a division of my copending application, Ser.No. 848,700, filed Nov. 4, 1977, and is being filed to comply with arequirement for restriction.

APPLICABILITY OF INVENTION

The method for effecting uniform distribution of a mixed-phase reactantstream to a fixed-bed of catalyst particles and the distributorapparatus therefor, encompassed by my inventive concept, are intended tobe applied to processes widely practiced within the petrochemical andpetroleum industries. Furthermore, the present invention is specificallydirected toward the distribution of a mixed vapor/liquid phase to afixed-bed of catalyst particles disposed within a catalytic reactionchamber. As such, it is well-suited for use (1) to distribute thereactant stream as it initially enters the reaction chamber and, (2) todistribute the mixed-phase effluent from one distinct bed of catalystparticles into the next succeeding lower bed of catalyst particles.Essentially, it is intended to utilize the present technique andapparatus in those catalytic reaction systems in which the vapor/liquidreactant stream flows cocurrently and downwardly. Similarly, it may beemployed to distribute two heterogeneous liquids.

Although mixed-phase reactions are found in both petroleum refining andpetrochemical processes, they appear to be more prevalent in the former;therefore, the following discussion will be limited to catalyzedhydrocarbon conversion reactions without, however, the intent to undulyrestrict the broad scope of the invention herein described. Mixed-phasehydrocarbon conversion reactions are generally effected in thoseprocesses where the fresh feed charge stock predominates in hydrocarbonsboiling above the naphtha boiling range -- i.e. above a temperature ofabout 400° F. In many cases, the vapor/liquid reactant stream consistsof liquid hydrocarbon constituents and a vapor phase which isconcentrated in hydrogen. Charge stocks include kerosene fractions,light and heavy gas oils (both atmospheric and vacuum) and asphaltenicblack oils containing constituents boiling above about 1050° F.Obviously, my invention does not rely for viability upon a particularhydrocarbonaceous charge stock, nor upon the particular reaction, orreactions being effected. The latter include hydrocracking,hydrogenation, desulfurization, denitrogenation, hydrotreating andcombinations thereof, all of which are hydrogen-consuming and,therefore, principally exothermic in nature.

Paramount to successfully effecting hydrogen-consuming reactions inmixed-phase processing is the uniform distribution of the reactantstream to the fixed-bed of catalyst particles. Where a given reactionchamber contains more than one distinct bed of catalyst particles,uniform distribution of the reactant stream from a preceding bed to asucceeding bed must also be effected. Tantamount to hydrogen-consumingreactions is the continuous intimate contact of hydrogen with thehydrocarbonaceous reactants, not only at the initial portion of thecatalyst bed, but also throughout the same as the reactant stream flowsdownwardly therethrough. The tendency for liquid and vapor constituentsto segregate and seek separate paths while traversing the bed ofcatalyst particles is commonly known and referred to as "channelling."As hereinafter indicated, the detrimental effects of channelling arewell known and a multiplicity of devices have been provided in attemptsto alleviate the same.

The technique and apparatus herein described is also directed towarduniform distribution of a mixed-phase reactant stream to a fixed-bed ofcatalyst particles; however, provision is made to provide for continuedintimate vapor/liquid contact as the reactant stream traverses thecatalyst bed. Briefly, the technique involves three distinct operationseffected in an apparatus having three individually distinct zones. Themixed-phase reactant stream, whether initially introduced into thereaction chamber, or emanating from one catalyst bed for introductioninto a succeeding catalyst bed, is first separated into a substantiallyliquid-free vapor-phase and a substantially vapor-free liquid-phase.These are subsequently re-mixed in a fashion which creates avapor/liquid froth, or foam-like mixture; this froth is re-distributedto the bed of catalyst particles. The use of the term "froth" in thepresent specification and appended claims is intended to allude to asemi-stable, intimate dispersion of a liquid in a vapor phase. Theliquid takes the form of extremely fine droplets which are dispersed ina continuous vapor phase which gradually collapses as the frothtraverses the bed of catalyst particles.

OBJECTS AND EMBODIMENTS

A principal object of my invention is to provide uniform distribution ofa mixed-phase vapor/liquid reactant stream to a fixed-bed of catalystparticles. A corollary objective is to afford a technique which producesa decrease in the vapor/liquid "channelling" effect as the reactantstream traverses the bed of catalyst particles.

A specific object of the invention as herein described is to provide avapor/liquid distributor device which can initially distribute thereactant feed stream to the uppermost catalyst bed, or functionintermediate two catalyst beds to distribute the mixed-phase effluentfrom an upper catalyst bed uniformly to the next succeeding lowercatalyst bed.

Still another object is directed toward uniform introduction of avapor/liquid mixed-phase, to a bed of catalyst particles, in a formwhich possesses the capability of resisting segregation and subsequentchannelling as it traverses the catalyst bed.

Therefore, in one embodiment, my invention is directed toward acocurrent, mixed-phase catalytic reaction system wherein a vapor/liquidreactant stream flows downwardly through a fixed-bed of catalystparticles, and encompasses the method for effecting the uniformdistribution of said reactant stream, which method comprises thesequential steps of: (a) introducing said vapor/liquid reactant streaminto a first catalyst-free area within said reaction system, and thereinseparating said stream into (i) an upwardly-flowing, substantiallyliquid-free vapor phase and, (ii) a downwardly-flowing, substantiallyvapor-free liquid phase; (b) reversing the flow of said separated liquidphase and forming a quasi-stagnant pool thereof; (c) reversing the flowof the separated vapor phase and introducing said vapor phase into alower second catalyst-free area, within said reaction system, disposedbelow said quasi-stagnant liquid pool; (d) passing said vapor phaseupwardly through said liquid pool and creating a vapor/liquid froththerewith; and, (e) distributing said vapor/liquid froth downwardly intoa bed of catalyst particles, disposed below said quasi-stagnant liquidpool, and across substantially the entire upper surface thereof.

This embodiment is further characterized in that the mixed-phasereactant stream is passed into said first catalyst-free area when it isinitially introduced into the catalytic reaction system. Further, it maybe passed into the first catalyst-free area as the effluent from anupper, preceding fixed-bed of catalyst particles.

In another embodiment, the invention herein described involves avapor/liquid distributor for effecting uniform distribution of amixed-phase reactant stream to the upper surface of a fixed-bed ofcatalyst particles disposed within a catalytic reaction chamber, saiddistributor having three annular-form catalyst-free volumes defined bythe interior surface of said chamber and three cylindrical walls inconcentric relationship therewith, and comprising, in cooperativerelationship: (a) a first cylindrical wall having (i) a greater nominaldiameter and height than second and third cylindrical walls and, (ii) aperforated first horizontal plate attached to the entire lower peripherythereof, said first cylindrical wall defining an outer firstannular-form volume with the interior surface of said reaction chamber;(b) a second cylindrical wall having (i) a greater nominal diameter thanthe third of said cylindrical walls and, (ii) an imperforate secondhorizontal plate attached to the entire upper periphery thereof, andbeing disposed intermediate the upper and lower periphery of said firstcylindrical wall and defining an intermediate second annular-form volumetherewith; (c) a third cylindrical wall disposed a finite distance belowsaid imperforate second horizontal plate and having its entire lowerperiphery attached to said perforated first horizontal plate, said thirdcylindrical wall defining an inner third annular-form volume with saidsecond cylindrical wall; and, (d) a third horizontal plate, attached atits outer periphery to the interior surface of said chamber, and havinga plurality of vertical tubular conduits attached to its upper surface,said tubular conduits (i) extending upwardly through said perforatedfirst horizontal plate and within said third cylindrical wall, andterminating a finite distance below said imperforated second horizontalplate, and, (ii) having a nominal diameter greater than the remainingapertures in said perforated first horizontal plate.

This embodiment may be further characterized in that the portion of thefirst horizontal plate betweeen the first and third cylindrical walls isimperforate. Other objects and embodiments of the present invention willbecome evident from the following more detailed description thereof. Inone such other embodiment, an imperforate horizontal washer-shaped discis disposed above the upper periphery of said first cylindrical wall,and (i) is attached to the interior surface of the catalytic reactionchamber and, (ii) extends inwardly over said first and secondcatalyst-free volumes.

CITATION OF RELEVANT PRIOR ART

It must be recognized and acknowledged that the prior art abounds with awide variety of devices to introduce (1) a mixed-phase reactant streaminto a catalytic reaction zone, (2) a vapor and/or liquid quench streamat an intermediate locus within a fixed-bed of catalyst particles and,(3) the mixed-phase effluent from an upper catalyst bed into the nextsucceeding lower catalyst bed. A perusal of the appropriate Classes23-288 and 208-146 indicates that this is the case.

For example, U.S. Pat. No. 2,981,677 (Cl. 208-146), issued Apr. 25,1961, is illustrative of a tri-conversion zone reaction chamber forutilization in a countercurrently-conducted catalytic process; liquidflows serially in a downwardly direction while the vaporous reactantflows upwardly. In essence, the apparatus consists of a horizontal platecontaining a plurality of vapor risers, in the form of bubble caps,through which liquid reactant flows downwardly; the plate supports thecatalyst bed into which the risers extend. A second horizontal plate isdisposed a finite distance above the catalyst bed, and contains aplurality of liquid downcomers through which liquid flows downwardlyinto the lower catalyst bed. The void volume between the catalyst bedand the second horizontal plate is referred to as a disengaging space;however, not all the vaporous material is separated therein. That is, aquantity thereof flows upwardly through the liquid downcomers in thehorizontal plate. Details of this operation, shown graphically in FIG. 1as conversion zone "A," are given in Column 3, Lines 31-47(downwardly-flowing liquid) and in Column 4, Line 60 through Column 5,Line 17 (upwardly-flowing vaporous constituents). The apparatus furthermakes provision for a liquid quench (conduits 48, 50 and 52 in FIG. 1)as described in Column 5, Lines 45-56. Initially, it must be noted thatthe apparatus is peculiar to countercurrent flow of gaseous and liquidconstituents. This, however, is not the most distinguishing feature withrespect to the vapor/liquid mixed-phase distributor claimed anddescribed herein. Most noteworthy is the fact that the apparatus of thereference makes no provision for a re-mixing of the separated liquid andvapor streams to create a froth for re-distribution to the nextsucceeding catalyst bed. Indeed, not only is it incapable of creatingsuch a froth, to do so would effectively destroy its intended function.Further, the apparatus does not effect virtually complete separation ofliquid and vapor; that is, throughout the confines of the device, liquidand vapor are in constant contact with each other.

U.S. Pat. No. 3,146,189 (Cl.208-146), issued Aug. 25, 1964, involves adevice for the initial distribution of a vapor/liquid feed stream to afixed-bed of catalyst particles. The liquid and vaporous components areseparately introduced into the catalyst bed through a horizontal platecontaining liquid downcomers and vapor downcomers, the latter extendinginto the bed of catalyst particles and designed to afford lateral vaporflow therethrough. Separation of the mixed-phase is effected in the voidspace between the inlet conduit and nozzle (30 and 31), and thehorizontal plate (17). Liquid collects on the plate to a level which isdetermined by the height of a plurality of cylindrical weirs (18);overflowing liquid is trickled downwardly into the catalyst particlesthrough an orifice (19) in the bottom of each weir. Vapors are preventedfrom entering the weirs by virtue of the created liquid seal. These arecaused to flow through the upper periphery of downcomers (20),downwardly therethrough and finally laterally through screening means(27) laterally into the catalyst bed. The vapor downcomers are adaptedwith an imperforate top plate (25) to prevent liquid from enteringtherein.

Although the reference recognizes the disadvantages of vapor/liquidchannelling, and provides a device for alleviating the same where thereactant stream initially contacts the catalyst bed, there is neitherrecognition of, nor provision made with respect to channelling whichoccurs throughout the remainder of the catalyst particles. In short,there is no re-mixing for the creation of froth and re-distribution ofthe same; further, the device is incapable of so doing.

U.S. Pat. No. 3,378,349 (Cl. 23-288), issued Apr. 16, 1968, directsitself to an inner-reactor mixed-phase distribution apparatus, theprincipal function of which serves to thoroughly admix the reactantstream effluent with a quench stream introduced between catalyst zones(Column 1, Lines 23-37 and Column 8, Lines 17-41). Whether gaseous, orliquid quench, the device is designed for the same to be introduceddirectly into the mixed-phase effluent emanating from the preceding,upper bed of catalyst particles.

In contrast to the mixed-phase distributor herein described, thereexists no separation of the reactant stream effluent into the individualliquid and vaporous phases. This is evident, not only from theconstruction of the apparatus (particularly as shown in FIG. 1), butalso in the description of the manner in which the device functions; thelatter is found in Column 5, Lines 1-21 and in Column 7, Lines 19-42. Asindicated, both liquid and vapor constituents flow through the samedowncomers immediately following disengagement from the previous bed ofcatalyst particles. Furthermore, there exists no creation of an intimatefroth of vapor and liquid for re-distribution into the succeeding bed ofcatalyst particles.

Still another mixed-phase distributing device is the subject of U.S.Pat. No. 3,524,731 (Cl. 23-288), issued Aug. 18, 1970. The device isintended to ease the ill effects resulting from maldistribution(channelling) of the mixed-phase components (Column 1, Line 65 throughColumn 2, Line 15). Essentially, the distributing apparatus consists ofa horizontal plate having inserted therein and therethrough a pluralityof short tubes and a plurality of longer tubes which are notchedproximate to the terminus above the horizontal plate. Functioning of thedistribution device is generally described in Column 2, Lines 26-49 andin Column 4, Lines 22-46; a perusal thereof indicates that the devicefunctions differently with high and low liquid flow rates. In the formersituation, only liquid flows downwardly through the shorter tubes, whileboth liquid and vapor flow through the longer tubes.

Although there could be considered a separation of liquid and vaporcomponents, only, however, in the situation of low liquid flow rates,there is no separation and re-mixing in such a manner as to create anintimate froth for re-distribution into the next succeeding bed ofcatalyst particles. The froth is not created merely by virtue of thefact that liquid components are flowing downwardly through tubes otherthan those through which the vaporous material is passed.

A flow distributor system somewhat similar to that illustrated in U.S.Pat. No. 3,146,189, hereinabove described, is the subject of U.S. Pat.No. 3,685,971 (Cl. 23-288), issued Aug. 22, 1972. The distributor islocated proximate to the reactant stream inlet port and is contiguouswith the inlet conduit. Its discharge end consists of a plurality ofdepending, spaced-apart concentric frusto-conical baffle members whichproduce an outward deflection of concentric, annular-form flow streamsto an equivalent proportional area of the lower catalyst bed. Aspreviously stated, there is recognition of channelling at the initialportion of the catalyst bed, and the device is intended to eliminate thesame by providing uniform distribution of the mixed-phase feed stream.There is no separation, re-mixing and re-distribution of the vapor andliquid within some intermediate portion of the catalyst bed.

U.S. Pat. No. 3,652,450 (Cl. 208-146), issued Mar. 28, 1972, No.3,697,416 (Cl. 208-146), issued Oct. 10, 1972 and No. 3,723,300 (Cl.208-146), issued Mar. 27, 1973, all involve techniques for theintroduction of quench streams into intermediate loci of fixed-bedcatalytic reaction zones and the various devices suitable for assuringproper, uniform mixing thereof with the mixed-phase reactant stream.

The foregoing delineated references, copies of which accompany thisapplication, are all directed toward mixed-phase catalytic processingand the uniform distribution of the reactant stream; therefore, they areappropriate to the subject matter of the present application. However,it is believed that, whether taken singly, or in combination with eachother, they neither anticipate, nor render obvious the technique andapparatus encompassed by the invention claimed and described herein. Insummation, there exists no teachings and/or recognition of virtuallycomplete separation of the mixed-phase reactant stream, a re-mixingthereof to create a vapor/liquid froth and the re-distribution of thefroth to a lower, succeeding bed of catalyst particles.

SUMMARY OF INVENTION

Distribution of a mixed-phase vapor/liquid reactant stream to afixed-bed of catalyst particles, in accordance with the invention hereindescribed and claimed, is founded upon recognition of the fact thatprovisions have not heretofore been afforded which will alleviatevapor/liquid segregation with resultant channelling as the reactantstream introduced across the upper surface of the catalyst bed traversesthe same. At best, the devices and techniques previously developed, andperhaps currently in use, do nothing more than distribute a multiplicityof small portions of the mixed-phase reactant stream onto a like numberof small areas of catalyst particles situated atop the confined bedthereof. As a result, each small portion virtually immediately commencesto segregate into distinct vapor and liquid streams which combine withother smaller vapor and liquid streams to seek channelled paths throughthe remainder of the catalyst particles. Similarly, the use of eithervaporous, or liquid quench streams, or both, to attenuate thetemperature rise experienced with exothermic reactions, has beenrecognized as a judicious operational technique. Many methods anddevices have been proposed, virtually all of which inject a multiplicityof smaller quench portions intermediate the catalyst bed; however, theeffect is the same as above noted. That is, these smaller portions seekto combine with each other to produce larger segregated portions whichcommence to channel through the bed. Through the practice of the presenttechnique, and the use of the device encompassed by my invention, themixed-phase vapor/liquid reactant stream is introduced into thefixed-bed of catalyst particles in a form which resists segregation,accompanied by channelling, as the reactant stream traverses thecatalyst bed.

The mixed-phase reactant stream is generally introduced into an uppervoid volume within the reaction chamber, and passes through a perforatedhorizontal plate under which is disposed the upper surface of the bed ofcatalyst particles; a similar perforated plate functions as catalystsupport means at the lower extremity of the catalyst bed. Where areaction chamber contains more than one bed of catalyst particles, eachis usually defined by such upper and lower perforated horizontal plates.The vapor-liquid distributor may be installed either in the uppermostvoid volume above the first bed of catalyst particles, or between thetwo perforated horizontal plates which separate one catalyst bed fromanother. In many situations, it will be advantageous to install thedistributor device in both locations. Where the exothermicity of thereactions indicates an expected temperature rise beyond the maximumallowable for protection of the catalyst particles, a quench stream isintroduced intermediate the catalyst beds. The present devicefacilitates the uniform, thorough distribution thereof, whethervaporous, or liquid, and also affords uniform quenching of the reactantstream, thereby avoiding localized hot spots.

Distribution of the vapor/liquid reactant stream, as described herein,involves three distinct steps, each of which is effected in a separate,individual zone of the apparatus. The mixed-phase, for discussion andillustration purposes being presumed to be the effluent from an upper,preceding bed of catalyst particles, passes through the perforatedcatalyst support plate into a vapor/liquid separation zone. Through theutilization of a plurality of separated cylindrical walls, all of whichare in concentric relationship with the interior surface of the reactionchamber, the mixed-phase is separated into an upwardly-flowing,substantially liquid-free vaporphase and a downwardly-flowing,substantially vapor-free liquid-phase. Liquid constituents initiallypassing through the perforated catalyst-support plate are prevented frombecoming admixed with the separated vapor-phase by an imperforatehorizontal washer-shaped disc which is disposed above the annular-formvolume through which vapor is flowing. All the elements of thevapor/liquid distributor are hereinafter more thoroughly and completelydescribed with reference to the accompanying drawings.

The flow of the liquid phase is reversed upwardly and a quasi-stagnantpool thereof is formed by over-flowing a cylindrical wall, or weir ontoa horizontal, perforated plate. Vapor-phase flow is also reversed, toassume a downward direction into a catalyst-free area (or volume) belowthe quasi-stagnant liquid pool. The vapors pass upwardly through theperforations, and into and through the quasi-stagnant liquid pool. Thisarea of the device is herein referred to as the re-mixing zone whereinthe vapor velocity upwardly into the pool of liquid is sufficiently highto prevent excessive liquid flow downwardly through the perforationsand, more importantly, to create the vapor/liquid froth. Where a vaporquench stream is utilized, it is introduced into the separatedvapor-phase proximate to the locus of vapor flow reversal. This isaccomplished through the use of a toroidal ring having perforationswhich direct the quench vapors downwardly. Similarly, liquid quench isintroduced through perforations in a toroidal ring disposed proximate tothe locus of liquid flow reversal. Quench streams may consist ofreactant stream components where appropriate. The term "quasi-stagnant"is used with reference to the liquid pool since it is almost immediatelyformed into the froth by the high velocity vapors.

The froth is directed through a plurality of downcomers which originatein a horizontal plate disposed below the perforated plate through whichthe vapors pass upwardly. These downcomers extend upwardly through theperforated plate and terminate in the re-mixing zone below the planecontaining the upper periphery of the cylindrical weir.Downwardly-flowing froth passes into a catalyst-free area above thehorizontal plate disposed immediately above the bed of catalystparticles, and is uniformly distributed through the apertures therein.

The vapor/liquid distribution apparatus encompassed by my inventiveconcept, and intended for utilization in fixed-bed catalytic reactionzones, will be further described and more fully understood uponreference to the accompanying drawings. Since these are presented forthe sole purpose of illustration and to foster a complete understandingof the device and the techniques involved, they are not considered ashaving been drawn to an accurate scale. For any given application, theprecise construction of the illustrated apparatus will be primarilydependent upon the reaction zone dimensions, the volume of catalysttherein and the relative quantities of vapor and liquid which areintroduced and traverse the entire catalyst bed.

BRIEF DESCRIPTION OF DRAWINGS

The various elements constituting the present vapor/liquid distributingapparatus are shown in the drawings as being substantially circular incross-section, in contrast to cross-sections which would be chordal inthe various sectioned plan views. As hereinbefore stated, the device canbe constructed so that sectioned plan views would illustrate acombination of circular and chordal cross-sections. The former aregenerally preferred from the standpoint of providing maximum internalreaction zone volumes in which to achieve the desired and intendedfunctions.

With brief reference to the drawings,

FIG. 1 is a partially-sectioned elevation of a fixed-bed catalyticreaction zone, generally indicated by numeral 1, and having a reactantstream inlet port and conduit 2 and a product effluent outlet port andconduit 3. When the reactions are principally exothermic in nature,thereby producing a temperature rise as the reactant stream traversesthe catalyst bed, the reaction zone is adapted with a vapor quench inletport 4 and/or a liquid quench inlet port 6. The use of such quenchstreams, for the purpose of attenuating the temperature rise experiencedwith exothermic reactions is well known to those having the requisiteskill in the petrochemical and petroleum refining arts. In thisillustration, the present apparatus is shown as being disposed betweenan upper catalyst bed 8 and a lower catalyst bed 9.

FIG. 2 is a partially-sectioned plan view taken upwardly substantiallyalong the line 2--2 of FIG. 1. Vapor quench inlet port 4 is shown ascommunicating with a toroidal ring 5, having a plurality ofdownwardly-directed apertures 5a; this construction is preferred sinceit enhances the uniform distribution of the vaporous quench stream.

FIG. 3 is a partially-sectioned plane view taken downwardlysubstantially along the line 3--3 of FIG. 1. Liquid quench inlet port 6is in open communication with a second toroidal ring having a pluralityof inwardly facing apertures 7a.

FIG. 4 is a partially-sectioned plan view taken downwardly substantiallyalong the line 4--4 of FIG. 1. Indicated are a plurality (in thisillustration 4) of weep holes 25 which are employed to prevent minorquantities of entrained liquid from accumulating on tray 24. It will benoted from FIGS. 2, 3 and 4, that all the components of the illustratedvapor/liquid distribution device are circular in cross-section andcoaxially-disposed within the catalytic reaction chamber. As shown inFIGS. 3 and 4, downcomers 22 are radially disposed, and incircumferential relationship with each other. The apertures andhorizontal plates 10 , 12, 20 and 24 are also radially disposed and incircumferential relation.

FIGS. 5 and 6 are similar to FIG. 3; however, they illustratemodifications to the layout of downcomers 22 and apertures 21 within theconfines of circular weir 23. In FIG. 5, the "grid" containingdowncomers 22 and apertures 21 is square in its configuration. Incontrast, FIG. 6 illustrates a "grid" which is essentially triangular inconfiguration.

DETAILED DESCRIPTION OF DRAWINGS

With specific reference now to FIG. 1, catalytic reaction zone 1 isshown as having two individual beds of catalyst particles 8 and 9; theseare separated by the vapor/liquid distribution device which constitutesmy invention. Essentially, the distributor has three separate zones eachof which performs a distinct function. Separation zone "S", betweenperforated, catalyst-support plate 12 and imperforate horizontal plate19a, serves to separate vapor from liquid in the mixture emanating fromcatalyst bed 8. Mixing zone "M", extending downwardly from imperforatehorizontal plate 19a to the perforated horizontal plate 20a, effects theintimate remixing of the previously separated vapors and liquid, therebycreating a froth. The froth is re-distributed to lower catalyst bed 9from re-distribution zone "R", being the void space between horizontalplate 24 and perforated plate 14, the latter disposed atop catalyst bed9.

The mixed-phase reactant stream, following the required degree ofpre-heat to achieve reaction zone temperature, is introduced intocatalytic reaction zone 1 by way of inlet port and conduit 2. Perforatedhorizontal plate 10, containing perforations or apertures 11, definesthe upper extremity of catalyst bed 8, and serves to initiallydistribute the reactant stream throughout the catalyst particles. Theappropriate art is replete with examples of devices to effect theinitial distribution of a reactant stream (existing in mixed-phase) to acatalytic reaction zone; one such device is the subject of U.S. Pat. No.3,685,971 (Cl. 23-288R), hereinbefore discussed. The use of such adevice is neither essential to, nor a part of the device encompassed bymy inventive concept. However, the vapor/liquid distributor hereindescribed may be installed in reaction chamber 1 in the area abovehorizontal plate 10 in order to effect initial distribution of thereactant stream to catalyst bed 8. The reactant stream traversescatalyst bed 8 and emanates therefrom through perforated, horizontalcatalyst-support plate 12; apertures 13 are obviously sized to inhibitthe passage of catalyst particles therethrough.

Reaction product effluent from catalyst bed 8 enters the separation zone"S" of the present vapor/liquid distributor through apertures 13; sincethe majority of mixed-phase operations involve reactions which areprimarily exothermic in nature, the temperature of the reactant streamrises as catalyst bed 8 is traversed. A common practice is to quenchthis stream to lower its temperature before it continues through theremainder of the catalyst disposed within the reaction zone. Inaccordance with the present illustration, a vaporous quench inlet port 4is provided; this is in open communication with a toroidal ring 5 havingapertures (see FIG. 2) disposed throughout its circumference to directthe vaporous quench in a downwardly direction. An imperforate horizontalwasher-shaped disc 18a is disposed above toroidal ring 5 to prevent theflow of liquid reactant stream constituents into the annular-form volumethrough which separated vapors are flowing downwardly. Washer-shapeddisc 18a is attached, at its outer periphery, to the interior surface ofreaction chamber 1, and extends inwardly to also cover an intermediateannular-form volume formed between cylindrical wall 20 and cylindricalwall 19. Preferably, the minor (inside) circumference of disc 18a isadapted with a downwardly extending cylindrical wall 18. The latterterminates below the upper peripheral edge of cylindrical wall 20.

Vaporous reactant stream effluent from catalyst bed 8 is caused to flowupwardly through the annular-form volume between cylindrical wall 20 andcylindrical wall 18. The upper edge of the former extends to a planeabove that which contains the lower edge of the latter in order toprevent liquid effluent from entering the annular-form volume createdwith the interior surface of the reaction zone. Vaporous effluent isadmixed with the quench vapors from toroidal ring 5, and passeddownwardly through the annular-form downcomer formed between theinterior surface of the reaction chamber and the cylindrical wall 20.These vapors flow, substantially free from liquid constituents,horizontally into the void volume between lower horizontal plate 24 andthe upper, perforated horizontal plate 20a which is attached to theentire lower periphery of cylindrical wall 20.

Liquid components in the effluent from catalyst bed 8 flow outwardlytoward the interior surface of catalytic reaction zone 1 by virtue ofimperforate horizontal top plate 19a which is attached to cylindricalwall of inverted U-shaped baffle 19; the latter forms a second,intermediate annular-form space with cylindrical wall 20. Liquid flowsdownwardly through the annular-form volume and is admixed therein withthe quench liquid from toroidal ring 7; the latter has aperturesdisposed along its circumferential surface which direct the quenchinwardly toward cylindrical weir 23. The mixture, substantially freefrom vapor, flows upwardly through a third annular-form volume betweencylindrical wall 19 and circular weir 23, creating a liquid "seal" thatrestricts the passage of vapor therethrough. A froth of vapors andliquid is created in mixing zone "M" as the liquid constituents whichoverflow cylindrical weir 23 are intimately contacted with the vaporsflowing upwardly through apertures 21 in horizontal plate 20a. The frothflows through a plurality of downcomers 22 into re-distribution zone"R", and therefrom through apertures 15 disposed in horizontal plate 14and into catalyst bed 9. Downcomers 22 are disposed in a manner whicheffects uniform distribution of the froth into the lower catalyst bed.Product effluent from catalyst bed 9 flows through apertures 17 disposedin catalyst-support plate 16, and are withdrawn from catalytic reactionzone 1 through outlet conduit and port 3.

FIG. 2, the partially-sectioned plan view taken upwardly substantiallyalong the line 2--2 of FIG. 1, is presented for the principal purpose ofillustrating the relationship of toroidal ring 5, having downwardlydirecting apertures 5a circumferentially disposed therein, andwasher-shaped disc 18a, adapted with cylindrical wall 18. Similarly,FIG. 3, the partially-sectioned plan view taken downwardly substantiallyalong the line 3--3 of FIG. 1, illustrates the relationship of toroidalring 7, having inwardly-directing apertures 7a circumferentiallydisposed therein, and circular weir 23. Also, the relationship of frothdowncomers 22, which extend through the horizontal plate 20a, and theapertures 21 which are radially and circumferentially disposed therein.FIG. 4, being the partially-sectioned plan view taken substantiallyalong the line 4--4 of FIG. 1, is intended to show the liquid weep holes25 (solid lines) which are circumferentially disposed in horizontalplate 24.

As previously set forth, FIGS. 5 and 6 are partially-sectioned planviews presented to illustrate the layout of froth downcomers 22 andapertures 21 in squared and triangular "grids", respectively. Although awide variety of tube spacings may be utilized, not necessarily withequivalent results, the present apparatus will utilize grid arrays whichare circumferential (FIGS. 3 and 4), square (FIG. 5) and triangular(FIG. 6); grids of the square and triangular configurations areparticularly preferred. It will be noted that the distribution deviceencompassed by my inventive concept permits the virtually completeseparation of vaporous and liquid phases; this affords the re-mixing tocreate an intimate vapor/liquid froth much the same as that found infractionation columns by the upward flow of vapors through a liquidphase. The device also affords quenching with vapor and/or liquid priorto the creation of the froth in order to quench the mixture uniformly.Other benefits and advantages will become apparent to those possessingthe requisite skill in the appropriate art.

I claim as my invention
 1. A vapor/liquid distributor for effectinguniform distribution of a mixed-phase reactant stream to the uppersurface of a fixed-bed of catalyst particles disposed within a catalyticreaction chamber, said distributor having three annular-formcatalyst-free volumes defined by the interior surface of said chamberand three cylindrical walls in concentric relationship therewith, andcomprising, in cooperative relationship:(a) a first cylindrical wallhaving (i) a greater nominal diameter and height than second and thirdcylindrical walls and, (ii) a perforated first horizontal plate attachedto the entire lower periphery thereof, said first cylindrical walldefining an outer first annular-form volume with the interior surface ofsaid reaction chamber; (b) a second cylindrical wall having (i) agreater nominal diameter than the third of said cylindrical walls and,(ii) an imperforate second horizontal plate attached to the entire upperperiphery thereof, and being disposed intermediate the upper and lowerperiphery of said first cylindrical wall and defining an intermediatesecond annular-form volume therewith; (c) a third cylindrical walldisposed a finite distance below said imperforate second horizontalplate and having its entire lower periphery attached to said perforatedfirst horizontal plate, said third cylindrical wall defining an innerthird annular-form volume with said second cylindrical wall; and, (d) athird horizontal plate, attached at its outer periphery to the interiorsurface of said chamber, and having a plurality of vertical tubularconduits attached to its upper surface, said tubular conduits (i)extending upwardly through said perforated first horizontal plate andwithin said third cylindrical wall, and terminating a finite distancebelow said imperforated second horizontal plate, and, (ii) having anominal diameter greater than the remaining apertures in said perforatedfirst horizontal plate.
 2. The vapor/liquid distributor of claim 1further characterized in that the portion of said first horizontal platebetween said first and third cylindrical walls is imperforate.
 3. Thevapor/liquid distributor of claim 1 further characterized in that saidtubular conduits are disposed through said perforated first horizontalplate such that the axes thereof are in the form of a circumferentialgrid.
 4. The vapor/liquid distributor of claim 1 further characterizedin that said tubular conduits are disposed through said perforated firsthorizontal plate such that the axes thereof are in the form of a squaredgrid.
 5. The vapor/liquid distributor of claim 1 further characterizedin that said tubular conduits are disposed through said perforated firsthorizontal plate such that the axes thereof are in the form of atriangular grid.
 6. The vapor/liquid distributor of claim 1 furthercharacterized in that a perforated fourth horizontal plate, attached atits outer periphery to the interior surface of said chamber, is disposeda finite distance below said third horizontal plate.
 7. The vapor/liquiddistributor of claim 1 further characterized in that an imperforatehorizontal washer-shaped disc is disposed above the upper periphery ofsaid first cylindrical wall, and (i) is attached to the interior surfaceof said chamber and, (ii) extends inwardly over said first and secondcatalyst-free volumes.